WIP 2

TODO.md

@@ -8,9 +8,9 @@
 * TODO comment in `visitors/function`
 * TODO comment in `serialize/parseFunction`
 * Deal with duplicate bindings:
-  * Hoisted sloppy functions
-  * `for (let x of x)`
-  * `x => { var x; }`
+  * Hoisted sloppy functions - actually no need, because `isFunction` means both are frozen anyway
+  * `for (let x of (() => x, [])) eval('x');` - done, but write test
+  * `function (x, _ = eval('x')) { var x; return x; }`
 * Tests
 * Tests for binding in higher scope which is shadowed still not being renamed
   e.g. `() => { let x = 1; { let x; eval('typeof a !== "undefined" && a = 2'); } return x; }` - make sure param `x` not renamed to `a`

lib/instrument/visitors/loop.js

@@ -22,7 +22,7 @@ const Statement = require('./statement.js'),
 	Expression = require('./expression.js'),
 	VariableDeclaration = require('./variableDeclaration.js'),
 	{AssigneeAssignOnly} = require('./assignee.js'),
-	{createBlock, createAndEnterBlock, createBindingWithoutNameCheck} = require('../blocks.js'),
+	{createBlock, createAndEnterBlock} = require('../blocks.js'),
 	{insertBlockVarsIntoBlockStatement} = require('../tracking.js'),
 	{visitKey, visitKeyMaybe, visitKeyContainer} = require('../visit.js');
 
@@ -98,15 +98,15 @@ function ForXStatement(node, state) {
 	// with all same bindings as init block. Accessing these vars from within right-hand side
 	// is temporal dead zone violation.
 	// https://github.com/overlookmotel/livepack/issues/323
+	// These bindings are in a different block, but just copy the binding objects themselves.
+	// This ensures that if any binding is frozen by `eval()`, the corresponding binding is too.
+	// e.g. `function() { let f; for (let x of (f = () => typeof x, [])) { eval('x'); } }`
+	// Without this, serializing outer function would allow `x` in `typeof x` to be mangled so it wouldn't
+	// be a TDZ violation any more.
 	state.currentBlock = parentBlock;
-	const initBindingNames = Object.keys(initBlock.bindings);
-	if (initBindingNames.length !== 0) {
-		const rightBlock = createAndEnterBlock('for', false, state),
-			fn = state.currentFunction;
-		for (const varName of initBindingNames) {
-			const binding = createBindingWithoutNameCheck(rightBlock, varName, {isConst: true});
-			if (fn) fn.bindings.push(binding);
-		}
+	if (Object.keys(initBlock.bindings).length !== 0) {
+		const rightBlock = createAndEnterBlock('for', false, state);
+		rightBlock.bindings = initBlock.bindings;
 	}
 
 	// Visit right-hand side